Fuel injection nozzle



Dec. 19, 1961 w. e. WEBSTER ETAL 3,013,732

FUEL INJECTION NOZZLE Filed Sept. 1, 1959 iww 0m, 27d Dow/2% v ATTORNEYS United States 3,013,732 Patented Dec. 19, 1961 The present invention relates generally as indicated to a fuel injection nozzle and more particularly to improvements in a fuel injection nozzle for gas turbines and the like.

At the present time so-called dual orifice nozzles are in extensive use and essentially such nozzles are formed with a primary fuel supply passage which leads to the primary discharge orifice of the nozzle by way of swirl slots or the like, which impart to the fuel a whirling motion so that upon leaving the orifice it is broken up into fine droplets and spread out in conical spray pattern form. Such nozzle is also provided with a secondary fuel supply passage through which fuel is supplied through a secondary discharge orifice (usually annular) disposed concentrically around the aforesaid primary orifice, and again, swirl slots are provided in the secondary fuel passage to impart whirling motion to the fuel for discharge in fine droplet and conical spray pattern form. Such nozzle usually has associated therewith a fiow divider so that at low fuel flows, the fuel is discharged only through the primary orifice to achieve elficient atomization while for greater fuel flows, the fuel is discharged from both the primary and secondary orifices, proper atomization being achieved by reason of the greater velocities through the nozzle.

Such dual orifice nozzles includes a holder and a nozzle body threadedly connected thereto, the nozzle body being a member which defines the outer wall of the secondary fuel passage, secondary swirl chamber, and secondary orifice. Such threaded joint is usually sealed by a suitable packing ring interposed between radially opposed shoulders of the holder and nozzle body. However, it has been found that under varying conditions of operation of the gas turbine with which the nozzle is used, such packing ring is not reliable as a leakproof seal and will, in time, evidently due to to alternate expansion and contraction of the nozzle parts, lose its effectiveness in preventing leakage of fuel through the threaded joint between the holder and nozzle body. Heretofore it has been impractical to braze or weld together these threadedly engaged nozzle parts, since, although the problem of fuel leakage may be solved thereby, it would then be substantially impossible to disassemble the holder and nozzle body for cleaning, adjustment, or replacement of internal parts thereof because the brazing or welding metal would inevitably find its way to the threads. Thus, if such nozzles of welded or brazed construction would become Wholly or partly inoperative due to foreign matter or wearing of parts therewithin, it would be necessary to discard them and replace them with new ones.

Such welded or brazed threaded joint enabling disassembly of the holder and nozzle body is the subject matter of our copending application and it is one principal object of this invention to provide a fuel injection nozzle in which the holder is detachable from the nozzle body and, when so detached, renders the interior parts of the nozzle readily accessible for cleaning, adjustment, or replacement. 7

Other objects and advantages of the present invention will become apparent as the following description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, comprises the features hereinafter fully described and particularly pointed out in the claims, the following description and the annexed drawing setting forth in detail a certain illustrative embodiment of the invention, this being indicative, however, of but one of the various Ways in which the principle of the invention may be employed.

In said annexed drawing:

The single FIGURE is a fragmentary cross-section view diametrically through a preferred form of fuel injection nozzle embodying the present invention.

Referring now in detail to the drawing, the holder 1 is herein shown as being in the form of an elbow of which one leg 2 is externally threaded at 3 up to an annular shoulder 4 which preferably lies in a plane perpendicular to the axis of such threads 3, said leg 2 being formed with a secondary fuel flow passage 5. Intersecting the passage 5 is the secondary fuel passage 6 formed in the other leg 7 of the holder 1 and connected to said passage 6 as by Welding is the end portion of the secondary fuel supply conduit 8 which has its other end (not shown) connected in Well-known manner to a suitable flow divider or the like, which is effective to supply fuel into said secondary conduit 8 in accordance with the demand for fuel required by the gas turbine or the like.

Located concentrically within the leg 2 of the holder 1 is a tubular insert 9 which has its inner end fitted into and brazed in an opening 10 which communicates with the primary fuel passage 11 formed in the leg 7 of the holder 1. The outer end portion of said tubular insert 9 isformed with circumferentially spaced radially extending legs 12. which also are secured by brazing or like expedient, in fixed position at the end of the secondary fuel passage 5.

Leading to the primary passage 11 and secured thereto.

as by welding, is the end portion of the primary fuel supply conduit 14 which has its other end (not shown) connected with a fuel supply source, usually a port which constant communication with the inlet of the aforesaid flow divider. Surrounding the primary andseco-ndary fuel supply lines 8 and 14 is a heat shielding tube 15 which is telescoped over the leg 7 of the nozzle body 1 and over a corresponding leg or boss (not shown) formed on the fuel flow divider valve.

Coming back now to the tubular insert 9, which is bored to provide the primary fuel passage 16, its outer end portion is internally threaded for screwing thereinto the externally threaded connector 17 which thus provides exposed axially extending external threads on which the primary nozzle 18 is screwed with its inner end in firm abutting engagement with the end of the tubular insert 9.

Said primary nozzle 18 has an enlarged head which is formed with a plurality of helically disposed grooves or swirl slots 19 on its periphery, and with a frusto-conical end portion which terminates in an axially extending lip 29 which, together with the frusto-conical wall 21 ary orifice 25 in fine droplet and conical spray pattern form.

Said primary nozzle 18 is also formed with the primary orifice 26 and, in addition, has the swirl producing pri mary plug 27disposed therein which, as shown, has a support spider or guide at one end and a swirl slot head at the other end disposed to impart swirling velocity to the fuel which is supplied from the primary fuel supply line 14 and flows through the passage 16 of the tubular insert 9, through the connector 17, and through the openings in the spider and the swirl slots in the head of the primary plug 27 for discharge in fine droplet and conical spray form from the primary orifice 26.

The nozzle body 24 previously referred to is for-med with internal threads which have threaded engagement with the threads 3 of the leg 2 of the holder 1 and said nozzle body 24 is adapted to be screwed on tightly until the internal shoulder 28 therein engages the annular end face of the holder 1.

Spot welded, or otherwise secured, on the nozzle body 24 is a shroud 29 which forms an annular air space around the discharge end portion of the nozzle body 24.

As shown, the internally threaded end of the nozzle body 24 terminates in an annular end surface 30 which is axially spaced from and parallel to the shoulder 4 of the holder 1. Positioned between the annular faces 4 and 30 and surrounding the threads 3 of the holder 1 is a refractory ring 31 made, for example, of carbon or like material, which is capable of withstanding the high temperatures to which the holder 1 and nozzle body 24 are subjected when the welding operation is performed. It has been found that the axial length of the refractory ring 31 should be slightly less (.010" to .020", for example) than the axial distance between the faces 4 and 30 so that no stress is imposed on said ring 31 when the nozzle body 24 is screwed onto the holder 1. As a matter of fact, it has been found that an axial clearance such as indicated above between the opposite ends of the refractory ring 31 and the surfaces 4 and 30 is not at all objectionable since the weld metal 32 is effectively prevented from flowing inward to the interengaged threads of the nozzle body 24 and the holder 1.

The drawing shows the assembled condition of the present fuel injection nozzle with a ring 32 of weld metal integrally joining the holder 1 and nozzle body 24 so as to form a safe fluid-tight joint which will not only prevent leakage of fuel but also loosening of the nozzle body 24 due to vibration.

However, despite the fact that the nozzle body 24 and holder 1 are thus inseparably secured together in leakproof manner and against loosening due to vibration, yet, if one so desires, the nozzle body 24 may easily be removed from the holder 1 for cleaning or servicing of the interior of the noule and then may he reassembled and rewelded to the holder 1.

Such disassembly is preferably done with a cut-off tool or the like as disclosed in the aforesaid co-pending application which is effective to cut away the welded section 32 to a width which is preferably at least equal to the axial length of the refractory ring 31, whereby, when the metal 32 is cut away down to the outside diameter of the ring 31, it is a simple matter to unscrew the nozzle body 24 from the holder 1 to perform the necessary cleaning or other servicing operations. Then, after the servicing operation has been completed the nozzle body 24 is rescrewed onto the holder 1 and rewelded to form an inseparable unitary assembly having a fluid-tight threaded joint.

From the foregoing it is clear that, when the nozzle body 24 is unscrewed from the holder 1, the outer wall of the secondary fuel supply passage, the outer wall 21 of the secondary whirl chamber, and the wall of the opening 23 may be inspected and cleaned. Furthermore, with the nozzle body 24 removed, the secondary swirl slots 19 are exposed for inspection and cleaning as is the conical surface and lip which define the inner walls of the secondary swirl chamber and of the secondary discharge orifice 25. Next, the primary nozzle 18 may be removed for cleaning or replacement by unscrewing the same from the connector 17, and then the primary plug 27 may be withdrawn from the primary nozzle 18, thereby providing access to the primary orifice 26, to the primary swirl chamber, and to the primary supply passage defined by primary nozzle 18 and also providing access to the primary swirl slots formed in the primary plug 27.

Other modes of applying the principle of the invention may be employed, change being made as regards the details described, provided the features stated in any of the following claims, or the equivalent of such, be employed.

We therefore particularly point out and distinctly claim as our invention:

1. A fuel injection nozzle comprising a holder having laterally adjacent primary and secondary fuel supply passages, a coaxial bore and counterbore respectively intersecting said primary and secondary passages; a tubular insert secured in said bore to isolate said passages from one another and to provide through said insert an extension of said primary passage, said insert being radially spaced from said counterbore to provide an annular extension of said secondary passage, said holder and insert terminating at one end in such concentric primary and secondary passage extensions and in concentric screw threads; a nozzle body and a primary nozzle concentrically disposed therein having detachable screw threaded engagement with the respective screw threads of said holder and insert and defining therebetween in succession a further extension of said secondary passage, a series of swirl producing slots, a secondary swirl chamber, and a secondary discharge orifice; and a primary plug removably fitted in said primary nozzle to define with the latter in succession a further extension of said primary passage, another series of swirl producing slots, and a primary swirl chamber; said primary nozzle having a primary discharge orifice through which fuel from said primary swirl chamber is adapted to be sprayed; said nozzle body, said primary nozzle, and said primary plug being rendered accessible for inspection, cleaning, replacement, or other servicing by reason of such detachability thereof.

2. The nozzle of claim 1 wherein said insert adjacent such one end thereof has radial legs engaging said counterbore to center that end of said insert in said holder.

3. A fuel injection nozzle comprising a holder and tubular insert secured therewithin respectively terminating at one end in axially offset and concentric screw threads of different pitch diameters and defining therebetween an annular secondary fuel supply passage concentrically between said screw threads; said insert having a primary fuel supply passage concentrically within the screw threads of smaller pitch diameter; a nozzle body having threaded engagement with the threads of larger pitch diameter; and a primary nozzle inside said nozzle body having threaded engagement with the threads of smaller pitch diameter; said nozzle body and said primary no-zzle defining a secondary discharge orifice which communicates with said secondary passage and which is accessible for cleaning or servicing upon unscrewing of said nozzle body, and a primary discharge orifice which communicates with said primary passage and which is accessible for cleaning or servicing upon unscrewing of said primary nozzle.

References Cited in the file of this patent UNITED STATES PATENTS ,590,772 Joyce Mar. 25, 1952 2,701,164 Purchas et al. Feb. 1, 1955 03,260 Olson et al. Mar. 1, 1955 8, 5 Watkins Mar. 17, 1959 

